Space shuttle mechanistic studies to characterize atomic oxygen interactions with surfaces

A materials interaction experiment has been approved to study atomic oxygen interaction mechanisms and develop coatings for Space Station elements requiring long-lived operation in the LEO environment. A brief summary of this experiment is presented and the required exposure conditions are reviewed

Working group written presentation: Atomic oxygen

Earlier Shuttle flight experiments have shown NASA and SDIO spacecraft designed for operation in low-Earth orbit (LEO) must take into consideration the highly oxidative characteristics of the ambient flight environment. Materials most adversely affected by atomic oxygen interactions include organic films, advanced (carbon-based) composites, thermal control coatings, organic-based paints, optical coatings, and thermal control blankets commonly used in spacecraft applications. Earlier results of NASA flight experiments have shown prolonged exposure of sensitive spacecraft materials to the LEO environment will result in degraded systems performance or, more importantly, lead to requirements for excessive on-orbit maintenance, with both conditions contributing significantly to increased mission costs and reduced mission objectives. Flight data obtained from previous Space Shuttle missions and results of the Solar Max recovery mission are limited in terms of atomic oxygen exposure and accuracy of fluence estimates. The results of laboratory studies to investigate the long-term (15 to 30 yrs) effects of AO exposure on spacecraft surfaces are only recently available, and qualitative correlations of laboratory results with flight results have been obtained for only a limited number of materials. The working group recommended the most promising ground-based laboratories now under development be made operational as soon as possible to study the full-life effects of atomic oxygen exposure on spacecraft systems

Material interactions with the Low Earth Orbital (LEO) environment: Accurate reaction rate measurements

To resolve uncertainties in estimated LEO atomic oxygen fluence and provide reaction product composition data for comparison to data obtained in ground-based simulation laboratories, a flight experiment has been proposed for the space shuttle which utilizes an ion-neutral mass spectrometer to obtain in-situ ambient density measurements and identify reaction products from modeled polymers exposed to the atomic oxygen environment. An overview of this experiment is presented and the methodology of calibrating the flight mass spectrometer in a neutral beam facility prior to its use on the space shuttle is established. The experiment, designated EOIM-3 (Evaluation of Oxygen Interactions with Materials, third series), will provide a reliable materials interaction data base for future spacecraft design and will furnish insight into the basic chemical mechanisms leading to atomic oxygen interactions with surfaces

Atomic oxygen

The effects of atomic oxygen (AO) on materials in aerospace environments are examined. Materials are categorized according to their susceptibility to AO. The degradation effects of AO are examined to determine which materials are most vulnerable. Classes of spacecraft materials are listed and correlated with a performance category. The spacecraft orbits sensitive to AO interactions are also listed. Correlations are presented of AO effects on materials and of spacecraft glow effects

Evaluation of bone excision on occipital area of simulated human skull

Surgical effects of bone and soft tissue tumours, whether for biopsy or full excision have been researched from as early as the 1970’s [1]. These researches though have as main focus the biological (histological) rather the mechanical aspects of the effects [2]. With technological advances in biomedical and biomechanical modelling, a plethora of researchers have been exploring the possibilities of understanding [3] or even predicting musculoskeletal behaviour under different loading conditions [4]. This research is seeking to bridge these two different facets by looking into the mechanical effects bone tumour surgery might have to the structural rigidity of a simulated human skull

Paper 4 : Schooling, identity and social connectivity

This paper will report on the progress of a large three year Australian Research Council (ARC) grant awarded to a multidisciplinary team of researchers in Victoria, Australia. The research, A multi-disciplinary investigation of how trauma and chronic illness impact on schooling, identity and social connectivity commenced in 2007 and is known as Keeping Connected (2007). The research is a collaborative grant in partnership with the Royal Children&rsquo;s Hospital Education Institute, in association with the Melbourne Graduate School of Education, University of Melbourne and the Centre for Adolescent Health, Royal Children&rsquo;s Hospital. The research aims to investigate qualitatively, longitudinally and through multiple perspectives how young people construct/reconstruct identity and relationships with schooling following disruption associated with chronic illness. Using a mixed methodology, but with a central focus on longitudinal qualitative studies from the perspective of the young people, the study aims to identify key elements of disruption or continued connection, and will illuminate identity issues of people facing this disruption at different age and schooling points. The research outcomes will support education and health practices and provide a differently focused empirical contribution to the literature on education and social connection. The paper works at mixing methods qualitatively, rather than focusing on the overall mixed method design of the study. Assemblages of social capital theory and sociomateriality may be a useful standpoint for the development of our empirical contribution.<br /

Sequence structure emission in The Red Rectangle Bands

We report high resolution (R~37,000) integral field spectroscopy of the central region (r<14arcsec) of the Red Rectangle nebula surrounding HD44179. The observations focus on the 5800A emission feature, the bluest of the yellow/red emission bands in the Red Rectangle. We propose that the emission feature, widely believed to be a molecular emission band, is not a molecular rotation contour, but a vibrational contour caused by overlapping sequence bands from a molecule with an extended chromophore. We model the feature as arising in a Polycyclic Aromatic Hydrocarbon (PAH) with 45-100 carbon atoms.Comment: 13 pages, 9 figures, accepted for publication in ApJ. A version of the paper with full resolution figures is available at: http://www.aao.gov.au/local/www/rgs/Sequence-Structure

Photodesorption of CO ice

At the high densities and low temperatures found in star forming regions, all molecules other than H2 should stick on dust grains on timescales shorter than the cloud lifetimes. Yet these clouds are detected in the millimeter lines of gaseous CO. At these temperatures, thermal desorption is negligible and hence a non-thermal desorption mechanism is necessary to maintain molecules in the gas phase. Here, the first laboratory study of the photodesorption of pure CO ice under ultra high vacuum is presented, which gives a desorption rate of 3E-3 CO molecules per UV (7-10.5 eV) photon at 15 K. This rate is factors of 1E2-1E5 larger than previously estimated and is comparable to estimates of other non-thermal desorption rates. The experiments constrains the mechanism to a single photon desorption process of ice surface molecules. The measured efficiency of this process shows that the role of CO photodesorption in preventing total removal of molecules in the gas has been underestimated.Comment: 5 pages, 4 figures, accepted by ApJ

Fast high fidelity quantum non-demolition qubit readout via a non-perturbative cross-Kerr coupling

Qubit readout is an indispensable element of any quantum information processor. In this work, we experimentally demonstrate a non-perturbative cross-Kerr coupling between a transmon and a polariton mode which enables an improved quantum non-demolition (QND) readout for superconducting qubits. The new mechanism uses the same experimental techniques as the standard QND qubit readout in the dispersive approximation, but due to its non-perturbative nature, it maximizes the speed, the single-shot fidelity and the QND properties of the readout. In addition, it minimizes the effect of unwanted decay channels such as the Purcell effect. We observed a single-shot readout fidelity of 97.4% for short 50 ns pulses, and we quantified a QND-ness of 99% for long measurement pulses with repeated single-shot readouts

Polycylcic Aromatic Hydrocarbons (PAH's) in dense cloud chemistry

Virtually all detailed gas-phase models of the chemistry of dense interstellar clouds exclude polycyclic aromatic hydrocarbons (PAH's). This omission is unfortunate because from the few studies that have been done on the subject, it is known that the inclusion of PAH's can affect the gas-phase chemistry strongly. We have added PAH's to our network to determine the role they play in the chemistry of cold dense cores. In the models presented here, we include radiative attachment to form PAH-, mutual neutralization between PAH anions and small positively-charged ions, and photodetachment. We also test the sensitivity of our results to changes in the size and abundance of the PAH's. Our results confirm that the inclusion of PAH's changes many of the calculated abundances of smaller species considerably. In TMC-1, the general agreement with observations is significantly improved contrary to L134N. This may indicate a difference in PAH properties between the two regions. With the inclusion of PAH's in dense cloud chemistry, high-metal elemental abundances give a satisfactory agreement with observations. As a result, we do not need to decrease the observed elemental abundances of all metals and we do not need to vary the elemental C/O ratio in order to produce large abundances of carbon species in TMC-1 (CP).Comment: Accepted to ApJ. Astrophysical Journal (2008) accepte